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ASTM International - ASTM E975-13

Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation

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Organization: ASTM International
Publication Date: 15 February 2013
Status: active
Page Count: 7
ICS Code (Steels): 77.080.20
significance And Use:

2.1 Significance-Retained austenite with a near random crystallographic orientation is found in the microstructure of heat-treated low-alloy, high-strength steels that have medium (0.40... View More

scope:

1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium Kα or molybdenum Kα X-radiation.

1.2 The method applies to carbon and alloy steels with near random crystallographic orientations of both ferrite and austenite phases.

1.3 This practice is valid for retained austenite contents from 1 % by volume and above.

1.4 If possible, X-ray diffraction peak interference from other crystalline phases such as carbides should be eliminated from the ferrite and austenite peak intensities.

1.5 Substantial alloy contents in steel cause some change in peak intensities which have not been considered in this method. Application of this method to steels with total alloy contents exceeding 15 weight % should be done with care. If necessary, the users can calculate the theoretical correction factors to account for changes in volume of the unit cells for austenite and ferrite resulting from variations in chemical composition.

1.6 Units-The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

TABLE 1 Calculated Theoretical Intensities Using Chromium Kα RadiationA

hkl

Sinθ/λ θ

f

Δf′ Δf" /F/

2

LP P T

B

N

2

R

(α iron, body-centered cubic, unit-cell dimension ao  = 2.8664Å):

110 0.24669 34.41 18.474 −1.6 0.9 1142.2 4.290 12 0.9577 0.001803

B

101.5

C

200 0.34887 53.06 15.218 −1.6 0.9  745.0 2.805  6 0.9172 0.001803

B

 20.73

C

211 0.42728 78.20 13.133 −1.6 0.8  534.6 9.388 24 0.8784 0.001803

B

190.8

C

(γ iron, face-centered cubic, unit-cell dimension a o  = 3.60Å):

111 0.24056 33.44 18.687 −1.6 0.9 4684.4 4.554  8 0.9597 0.0004594

B

 75.24

C

200 0.27778 39.52 17.422 −1.6 0.9 4018.3 3.317  6 0.9467 0.0004594

B

 34.78

C

220 0.39284 64.15 14.004 −1.6 0.8 2472.0 3.920 12 0.8962 0.0004594

B

 47.88

C

A  Data from "International Tables for X-Ray Crystallography," Physical and Chemical Tables , Vol III, Kynoch Press, Birmingham, England, 1962, pp. 60, 61, 210, 213; Weighted Kα1 and Kα2 value used (λ = 2.29092Å).B  Temperature factor (T = e−2M) where M = B(sin 2 θ)/λ2 and 2B = 0.71. Also N is the reciprocal of the unit-cell volume. C  Calculated intensity includes the variables listed that change with X-ray diffraction peak position.

Document History

ASTM E975-13
February 15, 2013
Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation
1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium Kα or...
June 1, 2008
Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation
1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium Kα or...
November 1, 2003
Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation
1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium K or...
July 10, 2000
Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation
1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium K[alpha] or...
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